Crystal Oscillator Circuit and Method for Starting Up a Crystal Oscillator

A crystal oscillator circuit comprises: a crystal oscillator; and an injection frequency generating circuit, the injection frequency generating circuit being configured to sense a signal of the crystal oscillator and amplify the sensed signal, the injection frequency generating circuit being further configured to inject the amplified signal to the crystal oscillator; wherein the crystal oscillator circuit is configured such that the crystal oscillator receives the amplified signal during an initial start-up period of the crystal oscillator and stops receiving the amplified signal at an end of the initial start-up period.